(under Print Production > Output Preview) to click on specific text and see its original properties. How to Fix the "Missing Font" Error
. Instead, they are generic labels used by PDF software to describe fonts that were not properly embedded or were renamed during the PDF creation process.
If you want a one-click solution, several open-source projects bundle all necessary CID-keyed fonts that cover F1–F6 (and sometimes F7 mapped to a generic fallback).